Poly (phosphine oxide) flame retardants for polymers

ABSTRACT

Compounds having the formula   WHEREIN R and R1 are, individually, methyl, ethyl or methoxy radicals; AR is benzene, naphthalene or anthracene and when AR is benzene, n and m are, individually whole integers of 0-2, inclusive, x is a whole integer of 2-6, inclusive and R and R1 can combine to form a saturated, six-membered, hydrocarbon ring in conjunction with two adjacent carbon atoms of the benzene ring; when AR is naphthalene, n and m are, individually, whole integers of 0-3, inclusive, and x is a whole integer of 2-4, inclusive; and when AR is anthracene, n and m are, individually, whole integers of 0-4, inclusive, and x is a whole integer of 26, inclusive, and flame-retarded polymers containing the same, are disclosed.

United States Patent 1191 Hoffman Nov. 4, 1975 1 1 POLY (PHOSHIINE OXIDE) FLAME 3,745,191 7/1973 Daigle Et al. 260/6065 P I RETARDANTS FO PQLYNIERS 3,745,197 7/1973 Toy et a1. 260/459 NP 3,790,638 2/1974 Kleiner et a1 260/6065 P' [75] Inventor: Joseph Adnan Hoffman, Somerville,

Primary Examiner-V. P. Hoke 73 Assignee; American c id Company, Attorney, Agent, or Firm-Frank M. Van Riet Stamford, Conn. C

7 ABSTRA T 1221 Filed: n 6. 23,1974 [5 1 Compounds having the formula [21] Appl. No.1 535,624

Related us. Application 13616 O [62] Pivision of Ser. No. 374,709, June 28, 1973, Pat. No. (A) R+CHIH4CHZCHZCMZL 3,895,048. /A 1 R, [52] [1.8. Cl. 260/453 N? [51] Int. (31. C086 6/00 wherein R and R are, individually, methyl, ethyl or [58] Field ofSearch 260/459 NP, 606.5 P methoxy radicals; AR is benzene, naphthalene or am thracene andwhen AR is benzene, n and m are, indi- [56] References Cited vidually whole integers of 0-2, inclusive, x is a whole UNITED STATES PATENTS integer of 2-6, inclusive and R and R can combine to 2,754,320 7 1956 Johnston 260/459 NP a gturatid l hydrocarbon mg m 2,881,147 4/1959 Graham..... 260/459 NP conluncm two Carbon atoms of the 3,113,973 12/1963 Hoffman 61 a1. 260/6065 P P fls mg; When AR 15 3311111919116, and 3,116,317 12/1963 Grayson et a1. 260/6065 P mdwldually. Whole Integers mcluslve, and X 15 3,213,057 10/1965 Ritt et a1, 260/6065 P 'a who1e integer of 2-4, inclusive; and when AR is an- I 3,234,543 11/1966 0111mm 6: 81.... 260/457 P thracene, n and m are, individually, whole integers of 3,306,937 2/1967 Clampitt et 3.1.1. 260/6065 P 0-4 inclusive and x is a hole hugger of 2 .6 inclug gg gg 132g $2 2 2 1 sive, and flame-retained polymers containing the e B a 3,663,502 6. 5/1972 Murray 61 1.... zoo/43.9.191 same are dsclpsed' I r 3,716,580 2/1973 Maier 260/6061'5 P 9 N0 Drawings 7 I POLY (PHOSPHINE OXIDE) FLAME RETARDANTS FOR POLYMERS CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisional of application Ser. No. 374,709, filed June 28, 1973 now U.S. Pat. No. 3,895,048; and is related to my copending application Ser. No. 374,728, filed of even date herewith, now US. Pat. No. 3,835,119, and entitled POLY (PHOSPl-IINE OXlDE)-AMMONIUM POLY-PHOSPHATE F LAME- ARDANTS.

BACKGROUND OF THE INVENTION The use of alkylenebisphosphine oxides to flameproof thermoplastic polymers'is known, see US. Pat. No. 3,284,543. These compounds, although effective flame-retardants for thermoplastics, are effective only at high concentrations of about 20-25% in most polymers. Moreover, these prior art compounds have been found to be relatively incompatible with many polymers such as, for example, polypropylene. As a result, they are extremely difficult to incorporate into such polymers by conventional extrazsion and injection molding techniques since they tend to exude from the polymer. Consequently, uniform dispersions of the alkylenebisphosphine oxides are difficult to obtain. A third, sometimes more detrimental, disadvantage of these known flame-retardants is that they are relatively -water-soluble and in certain applications of the flameproofed polymers, such as in components of clothes washers and dishwashers, they tend to beextr'acted from the polymer. As a result, the polymer becomes more readily flammable andultirnately fails to pass the Unde'rwriters Laboratory test of acceptable flameretardance.

SUMMARY l have now discovered that these and other less objectionable deficiencies of the alkylenebisphosphine oxides can be overcome, and excellent flame-retardant properties can be achieved, by incorporating into thermoplastic polymers a compound conforming to the formula set forth hereinabove. These novel compounds impart flame-retardancy to thermoplastic polymers at relatively low concentrations, are easily incorporated into the polymer substrate and do not leach out of the polymer when it is used in conjunction with water after having been formed into a particular article of manufacture.

DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS The compounds found to be effective in flame-proofing thermoplastic polymers according to the present invention conform to at least one of the following formulae wherein R2, R, R, R5, R6 and R are, individually,

methyl, ethyl or methoxy radicals, and R an'd R can combine to form a saturated, six-membered, hydrocarbon ring in conjunction with two adjacent carbon atoms of the benzene ring; a and b are, individually,

whole integers of 0-2, inclusive; c and d are, individually, whole integers of 0-3, inclusive; 2 and f are, indi-.

vidually, whole integers of 0-4, inclusive; w is a whole integer of 2-6, inclusive; y is awhole integer of -2-4, in-

-- thyl)phosphonylmethylene]tetralin;

elusive; and zis a whole integer of 2-6, inclusive.

Among the preferred compounds are those represented by Formula I, including 5,8-bis[bis(2-cyanoel-,4-bis[bis(2- cyanoethyl)phosphonylmethylenej-Z,3,5,6-tet- Y ramethyl benzene; l,2,4,5-tetrakis[bis(2-cyanoethyl)- cyanoethyl)phosphonylmethylene]naphthalene; 2,3 ,6-

tris [bis( 2-cyanoethyl )phosphonylmethylene]naphthalene; phonylmethylane ]anthracene;2,6,9,'l O-tetra[bis(2- cyanoethyl )phosphonylmethylene]anthracene; bis[bis( Z-cyanoethyl)phosphonylmethylene1-2- methoxy naphthalene; 2,3-bis[bis(2-cyanoethyl )phos- I phonylmethylene]-6,7-diethylanthracene and the like.

The compounds of the instant invention are readily prepared by reacting bist2-cyanoethyl)phosphine oxide with the appropriately substituted halornethyl aromatic compound, in accordance with the general reaction. a

\ base -(Crux), (NCCHZCHJZPH I ll cmP-tcmcmcm,

2,4-bis bi s( 2-'cyanoethyl )phosphonylme- 2,3,6-tris[bis(2-cyanoethyl)phos- I .wherein X is a halogen and x, m, n, R, R and AR are as set forth above.

The intermediate halomethylated aromatic compounds may conveniently be prepared by reacting the corresponding benzene; naphthalene or anthracene with formaldehyde and a hydrogen halide e.g. hydrogen chloride; hydrogen bromide etc., according to known procedures such as those disclosed in US. Pat.

. Nos. 2,945,894; 2,951,100; 2,973,391; and 3,069,480.

Alternatively, chlorination of the alkyl group or groups of the appropriate methyl benzene, methyl naphthalene or methyl anthracene in the presence of suitable catalysts, see US. Pat. No. 2,926,202, 'or with chlorine absorbed on zeolite and under reactive conditions, see US. Pat. No. 2,956,084, may be effected.

The novel compounds of the instant invention are.

prepared according to the above general reaction in an organic solvent which is inert to the reaction and the components thereof. Methanol has been found to be a convenient solvent, however, other alcohols may also "be used. The reaction is best conducted in the presence of a proton acceptor such as a strong base e.g. potassium or sodium hydroxide, in amounts equivalent to the amount of hydrogen halide evolved.

The reaction is conducted at a temperature ranging from about 10 to about 60C. under atmospheric pressure. Subatmospheric or superatmospheric pressure can be used, if desired. No catalysts are necessary.

Thecompounds represented by Formula A, above, may be incorporated into the thermoplastic'polymers to which they are. to impart flame-retardance in amounts ranging from about 10% to about by weight, based on the weight of the polymer.

'The poly (phosphine oxides) may beincorporated into the polymers by any known method. For example, the oxide may be combined with the polymer by milling the two on a two-roll mill, mixing in a Banbury mixer, extrusion, injection molding and the like. The oxide *may also be incorporated into the polymer by adding it to the polymerization media during the polymer manufacture, provided the ingredients, catalysts etc. therein are inert thereto.

The thermoplastic polymers into which the novel poly (phosphine oxides) may be incorporated to produce the novel compositions of the instant invention are generally those produced from at least one ethylenically unsaturated monomer, wherein the monomer, or monomers, are polymerized, by any known method, via the st? fienic unsaturation therein. Preferred examples of polymers conforming to this definition include the polyolefins i.e. those polymers produced from ethylene, propylene etc. including copolymers thereof with such monomers as vinyl acetate etc. and homopolymers thereof i.e. polyethylene; polypropylene etc.; I may also use such polymers as the linear aromatic polyesters such as polyethylene terephthalate; polybutylene terephthalate; poly( l,4-cycloheXanedimethylene)- 'terephthalate etc.; the polyalkylene oxides such as polyethylene oxide; nylon; butadiene polymers such as the so-called impact polymers" i.e. acrylonitrilebutadiene-styrene polymers; acrylonitrile-styrenemethyl methacrylate grafted polybutadiene etc. Further examples of applicable polymers which may betl'ameproofed using my novel compounds are set forth in U.S. Pat. No. 3,284,543, referred to above, and hereby incorporated herein by reference.

it is. within the scope of the'present invention to in corporate such ingredients as plasticizers, dyes. pig- ILLUSTRATIVE METHOD PREPARATION OF p-DIBROMOMETHYL DURENE CH CH BrCH CH- Bir cu, on,

g A solution of 1760 ml. of concentrated sulfuric acid in 1740 ml. of glacial acetic acid is prepared. A slurry i of 444 parts of durene, 580 parts of paraformaldehyde and 1900 parts of sodium bromide in 3720 ml. of gla-- cial aceticacid is heated to C. and the sulfuric acid solution is added thereto over a period of 3 hours to give a thick, cream-colored slurry. The slurry is heated at C. for 1 hour, cooled to 5C. and filtered. The resultant filter cake is washed three times with 400 ml. of acetic acid, reslurried twice in 4000 ml. of water, reslurn'ed again twice in 2500 ml. of 5 sodium bicarbonate solution and again twice in 5000 ml. of water. The recovered filter. cake is then dried at 50C. 992 parts of the desired product, p-dibromomethyl durene, m.p. 2l4.52l5C.,are recovered. The product'is a white powder. The yield is 93%.

, EXAMPLE 1 A slurry of 880 parts of bis(2-cyanoethyl)phosphine oxide and 819 parts of the p-dibromomethyl durene produced above in 13,000 ml. of methanol is prepared and stirred as 374 parts of potassium hydroxide in 1800 ml. of methanol are addedthereto at such a rate as to maintain the temperature below 40C. The slurry is heated to reflux and, after 30 minutes, cooled to 5C.

and filtered. The resultant filter cake is reslurried three times in 1800 ml. of acetone, filtered, reslurried twice 1 in 10 liters of water, fiitered and dried to yield 1130 parts of thylene]-2,3,5,6-tetramethyl benzene. The product is a white powder having a melting point of 299-300C. The crude product is then recrystallized from boiling dimethylformarnide to yield 1817 parts in two crops. Final melting point is 308308.5C.

EXAMPLE 2 Following the procedure of Example 1, there is ohtained l,2,4,5-tetrakis[bis(2-cyanoethyl)phosphor:yimethylenelbenzene from l,2,4,5-tetrabromornetiiyl benzene and bis(2-cyanoethyl)phosphine oxide. The product has a melting point of 345-347C.

EXAMPLE 3 Again following the procedure of-Example 1, bi's(2- cyanoethyl )phosphine oxide and 2,4,6-tribromornethyl benzene are reacted to produce 2,4,6--tris{bis(2-cyanoethyl)phosphonylmethylenelmesitylen-e having a meltmg point of 237241C.

1 ,4-bis[ bis( 2-cyanoethyl )phosphonylmamelting point of 201-203c 5. EXAMPLE 4 l,4-dibromomethyl benzene is reacted with bis(2- cyanoethyl)phosphine oxide according to the procedures set forth in Example 1 to yield 1,4-phenylenebis[- bis(2-cyanoethyl)phosphonylmethylene] having 8.

EXAMPLE 5 Again using the technique of Example 1-, 1,3-dirnethyl-4,6-dih"'vmornethyl benzene is reacted with bis(2- cyanoethyiltphosphine oxide to yield 4,6-bis[bis(2-' cyanoethyl)phosphonylmethylene]-1 ,3-dimethyl benzene having a melting point of 151l53C.

EXAMPLE 6 The procedure of Example 5 is again followed except that the halobenzene intermediate is replaced by 1,4- dimethyl-2,5-dibromomethyl benzene. 2,5-Bis[bis(2- cyanoethyl)phosphonylmethylene]-1,4-dimethyl benzene, having a melting point of 242-245C., is recov ered.

EXAMPLE 7 When the procedure of Example 5 is again followed except that the halobenzene intermediate thereof is replaced by 2,5-dibromomethyl-l,4dimethoxybenzene, 2,5-bis[bis(Z-cyanoethyl)phosphonylmethylene]-1,4- dimethoxyoenzene, having a melting point of 22923 1C., is recovered.

EXAMPLE 8 Again following the procedure of Example 1, 1,5- dibromomethyl naphthalene is reactedwith bis(2- not has a melting point of 320330C.

EXAMPLE 10 The procedure of Example 8 is again followed except that the halobenzene intermediate is replaced by 5,8- dibromomethyltetralin. 5,8-Bis[bis(2-cyanoethyl) phosphonylmethylene]tetralin having a melting point of 228-230C. is recovered. r

EXAMPLE 1 1 When the procedure of Example 1 is again followed 7 except that the halobenzene intermediate is replaced by 2,4-dibromomethyl-1,3,5-trirnethylbenzene, 2,4- bis[bis(2-cyanoethyl)phosphonylrnethylene1-1 ,3,5- tn'methylbenzene having a melting point l74l76C. is recovered.

- Following the procedures of Example 1, above, various other poly (phosphine oxides) are produced by reacting bis(2-cyanoethyl)phosphine oxide with various bromomethyl benzenes, naphthalenes and anthracenes.

The various charge materials and the products pro duced therefrom are set forth in Table 1, below.

EXAMPLE 21 To polypropylene containing 0.1% of pentaerythriyl (3,51di-t-butyl-4-hydroxyphenyl)propionate tetrakis and 0.25% of distearylthiodipropionate is added 10%, by weight, based on the weight of the polymer, of the 1,4-bis-[bis(Z-cyanoethyl)phosphonylmethylenel- .2,3,5,-tetramethylbenzene of Example 1 by milling at 350F. on a standard plastic mill. The resultant composition is then compression molded into bars (1% inch X 5 inches & inch) at 400420F, The bars are then naphthalene methylene]-2-methoxy naphthalene cyanoethyl)phosphine oxide utilizing a /50 mixture of methanol and dimethylsulfoxide as solvent. The resultant product, 1,5-bis'[bis(2-cyanoethyl)phosphonylmethylenelnaphthalene has a melting point of 2262 28C.

EXAMPLE 9 Following the procedure of Example 8, there is obtained 9,10-bis[bis(2-cyanoethyl)phosphonylmethylenelanthracene from bis(2-cyanoethyl)phosphine oxide and 9,lO-dibromomethylanthracene. The prodtested according to ASTM D635- horizontal burning test modified using 34 test specimens. The flammabih ity rating is self-extinguishing.

When a similar amount of the compound of Example 1 of US. Pat. No. 3,284,543 is incorporatrd into the same polymer in the same manner and molded and tested, as above, the flammability rating is ffree-burnmg."

EXAMPLES 22-26 Various of the novel poly (phosphine oxides) of the instant invention is dry blended at 10%, by weight, based on the weight of the terephthalate, with polyethylene terephthalate and the dry blend is melted and stirred under nitrogen for 5-6 minutes at 300 -3l0C. The resultant mixture is then cooled, ground to a powder and laminated onto a fiberglass sheet by compression molding at 600F. The recovered laminated sheets are then cut into strips 2 inches X 6 inches X 0.030 inch and tested according to the Oxygen Index method of cording to the above Oxygen Index Test, results similar t to those shown in Table Ii were achieved.

EXAMPLES 42-58 Following the procedure described for Example 21, various poly (phosphine oxides) of the instant invention are milled with various polymers and tested ac,- cording to the testset forth therein. The results are set ASTM D2863-70 modified to accept the above test fO in Table fi Table IV Ex. Arylenebisphosphene Oxide Polymer Test Results 42 That of Ex. 2 15% Polyethylene passed 43 That of Ex. 3 10% Polybutylene terephthalate do. 44 That of Ex. 5 Polypropylene do. 45 That of Ex. 6 10% Poly( l,4-cyclohexanedimethylene) do.

terephthalate 46 That of Ex. 7 v 10% Same as Ex. 42 do. 47 That of Ex. 12 10% Polypropylene do. i 48 That of Ex. 13 10% Polypropylene do.

49 That of Ex. 14 l5% Same as Ex. 42 do. 50 That of Ex. 15 10% Polyethylene do. 51 That of Ex. 17 10% Polypropylene do. $2 That of Ex. 18 10% do. do. 53 That of Ex. 19 10% do. do. 54 That of Ex. 20 10% do. do. 55 That of Ex. 8 10% do. do. 56 That of Ex. 9 10% do. do. 57 That of Ex. 10 12% do. do. 58 do. do.

That of Ex.

specimens. In this test, the higher the oxygen index, the

better the flame-retardance. The results are set forth in Table ll, below. Additional sample strips are also subjected to hot water leaching according to Underwriters Laboratory Water Extraction Test, Subject 746, Mar. 1, I957, paragraph E6 and then burned. The water extraction test requires that the samples be immersed in water at 70C. for 7 days, the water being changed daily for the first 5 days. The samples are dried in a dessicator after the immersion tests and before they are sub jected to the above ASTM Oxygen Index test. The results are set forth in Table Ill, below.

Table 11 EXAMPLES -41 When the products. produced in Examples 57 and 12-20 were tested in polyethylene te-rephthalate ac- I claim: I. A flame-retarded composition comprising (I) a polyolefin or a linear aromatic polyester and (2) a flame-retarding amount of a compound having the formula V V Aiu-cn P-tcrt cn cn 1,

wherein R and R are, individually, methyl, ethyl or methoxy radicals, AR is benzene, naphthalene or anthracene and when AR is benzene, n and m are, individu-v ally, whole integers of 0 2, inclusive, .1: is a'whole integer of2-6, inclusive, and R and R can combine to form a saturated, six-membered hydrocarbon ring in conjunction with two adjacent carbon atoms of the benzene ring, when AR is naphthalene, n and m are, in dividually, whole integers of 0-3, inclusive, and x is a whole integer of 2-4, inclusive, and when AR is anthras cene, n and m are, individualiy, whole integers (510-4,

inclusive, and x is a whole integer of 2-6, inclusive.

2. A composition according to claim 1 wherein (I) is a polyolefin. i

3. A composition according to claim 1 wherein l is polypropylene.

4. A composition according to claim 1 wherein (l) is a linear aromatic polyester.

.5. A composition according to claim 1 wherein (l).is 

1. A FLAME-RETARDED COMPOSITION COMPRISING (1) A POLYOLEFIN OR A LINEAR AROMATIC POLYESTER AND (2) A FLAME-RETARDING AOUNT OF A COMPOUND HAVING THE FORMULA
 2. A composition according to claim 1 wherein (1) is a polyolefin.
 3. A composition according to claim 1 wherein (1) is polypropylene.
 4. A composition according to claim 1 wherein (1) is a linear aromatic polyester.
 5. A composition according to claim 1 wherein (1) is polyethylene terephthalate.
 6. A composition according to claim 1 wherein AR is benzene, R and R1 are methyl and x, n and m are
 2. 7. A composition according to claim 1 wherein AR is benzene, x is 4 and n and m are
 0. 8. A composition according to claim 1 wherein AR is naphthalene, x is 2 and n and m are
 0. 9. A composition according to claim 1 wherein AR is benzene, R is methyl, x is 2, n is 2 and m is
 0. 